LPUART_TransferSendNonBlocking() with framing errors

I'm using LPUART_TransferSendNonBlocking() to send a string (in the example below it's a 4 character string K2\r\n (where the last to are carriage return & line feed) )

However when I look the output (top line) there appear to be random pauses in the middle of the string causing framing errors. In the example below these delay are only of the orer of ms but on soem occasions it's been over a second.